Analysis And Optimization Of Beam Opening Angle Of Torsion Beam Suspension To Improve Frequency Response Characteristics Of The Whole Vehicle

The car is a more complex rigid-flexible coupling system,affected by external interference and random input,the driver in the process of operating the car in the form of working conditions also become complex and changeable.Vehicle system dynamics has always been a hot spot and a focus of research,focusing on the kinematic and dynamic characteristics of the vehicle resulting from the manipulation of the vehicle.At the same time,the suspension system as one of the important assembly parts of the car,its design has an important impact on the handing stability,ride comfort and passability of the car and other performance,but also affects the driver and passenger driving and riding experience.The torsion beam rear suspension is extensively used in various economical SUV and MPV sedan models at this stage because of its simple structure,small design space,low production cost and other advantages,so it has become the main form of rear suspension for most front-drive vehicles.When the vehicle turns and brakes under relatively harsh road conditions,the beam of the torsion beam suspension acts as a stabilizer bar,which stabilizes the body roll and steering,so it is necessary to design a reasonable beam opening angle of suspension.Therefore,it is necessary to design a reasonable beam opening angle to improve the performance of suspension and vehicle.This research aims to analyze,design,and optimize the structure of the torsion beam suspension to enhance its overall performance and provide theoretical guidance for the design of specific suspension structures.The optimized structure of the torsion beam suspension can also offer design concepts and practical references for improving vehicle handling stability.First,through the vehicle three-dimensional model of the test data and reference to the actual parameters of the vehicle provided by the enterprise,the whole vehicle rigid-flexible coupling model with front Mac Pherson and rear torsion beam suspensions is constructed by multi-body dynamics software.On this case,the suspension and vehicle dynamics models are adjusted.Then,taking the torsion beam suspension as the research object,its kinematic characteristics are analyzed in detail,and the expressions of wheel alignment parameter are deduced.The reasons why the change of suspension roll stiffness and left and right wheel load transfer affect the handling stability are explained,and the relationship between the beam opening angle of the torsion beam suspension and the suspension K&C characteristics and the influencing mechanism are analyzed in detail.Secondly,in view of the 3-DOF vehicle dynamic model thinking over the body roll,the transfer function of response index relative to the steering wheel angle is derived.The evaluation index of the vehicle frequency response characteristics is determined.Based on the swept-sine input simulation,the system reveals the influence mechanism of the change of the beam opening angle of the torsion beam suspension on the frequency response characteristics of the vehicle.Through co-simulation,the variation law of the frequency response characteristic index of the whole vehicle in the low frequency and high frequency ranges under different beam opening angles is obtained.The nonlinear relationship between the frequency response characteristic index of the whole vehicle and the beam opening angle in the whole space design is also obtained.The evaluation index of the vehicle’s steady-state response is determined,and the nonlinear relationship between the beam opening angle and the steady-state handling response index in the entire space design is discussed based on the constant radius corning simulation.Finally,an effective and reliable optimization method is proposed.Taking the beam opening angle is the optimization variable,by means of the genetic algorithm NSGA-Π,and then the multi-objective optimization is executed with the vehicle frequency response characteristic index at 0.5Hz under the swept-sine input simulation as the optimization objective.Comparing the optimized results,it can be seen that when the beam opening angle is about 85°,the frequency response characteristic index of the whole vehicle reaches the optimum,which is the optimal beam opening angle.And following optimization,the findings indicate that the handling stability of the car in the low frequency band has been effectively improved.